Ala Moana Swell Statistics, February: All Swell – Any Wind

This chart describes the variation of swells directed at Ala Moana through an average February. It is based on 2664 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the best grid node based on what we know about Ala Moana. In this particular case the best grid node is 39 km away (24 miles).

The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast only 0.6% of the time. Green and yellow show increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell happens.

The diagram implies that the prevailing swell direction, shown by the largest spokes, was SSW, whereas the the dominant wind blows from the S. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Ala Moana and away from the coast. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are surfable at Ala Moana, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical February, swells large enough to cause good for surfing waves at Ala Moana run for about 99% of the time.

IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.